The present invention relates to an open-end spinning machine with an impurity-removal device for removing dirt, soil, debris, plant matter and like impurities separated from fibers by sliver opening devices associated with the spinning stations of the machine.
Such impurity-removal devices are generally known in the state of the art, as described, e.g., in German Patent Publications DE Patent 23 56 180, DE-AS 26 34 770 or DE-OS 26 58 752.
German Patent Publication DE Patent 23 56 180 discloses rotor spinning units of an OE (i.e. open end) spinning machine with a conveyor belt arranged below the impurity-discharge opening of the open-end spinning units and traveling in the longitudinal direction of the machine, which conveyor belt receives and removes the impurities released during the opening of the sliver.
A potential problem with such impurity-removal devices is that tufts of fibers may form over the course of time in the area of the impurity-discharge openings by the settling of impurities and fibers. Such fiber tufts could be drawn back by suction into the area of the opening cylinder and possibly delivered therefrom into the spinning unit, which would then significantly disturb the spinning operation. In order to prevent such tufts of fibers from being able to form, a brush-like cleaning element is arranged on the conveyor belt the bristles of which cleaning element extend into the area of the impurity-discharge openings of the spinning units as the belt travels.
In the known spinning machines, the spinning units are arranged in two aligned rows essentially back to back along opposite sides of the machine. At the ends of the machine, the endless conveyor belt in the known impurity-removal device is deflected to reverse its course of travel and move along the opposite side of the machine, thereby for the removal of the impurities accumulating on the other side of the machine. The cleaning element is permanently arranged on the conveyor belt.
A similar impurity-removal device for open-end spinning machines is also described in German Patent Publication DE-OS 26 56 752. In this known device, a tangential belt is provided as a transport means for cleaning elements and serves at the same time as an impurity-removal means. This tangential belt, which is preferably a reciprocating belt, carries several differently designed cleaning elements arranged in series and collected into a group. The cleaning elements are fixed in a detachable and replaceable manner in holders which are permanently arranged on the tangential belt and are delivered during the travel of the tangential belt to the components of the spinning units which are endangered by impurities. That is, the cleaning elements can be removed as needed from the stationary tangential belt and replaced, if necessary, whereas during the travel of the tangential belt the cleaning elements are immovably fixed on the tangential belt.
Moreover, German Patent Publication DE-AS 26 34 770 describes an impurity-removal device for open-end spinning machines in which device an impurity-removal belt is arranged below the impurity-discharge openings of the sliver opening devices. The impurity-removal belt is arranged along the upper side of an air conduit comprising a through slot. The impurity-removal belt has an opening which provides communication between the air conduit and the impurity-discharge openings of the individual sliver opening devices. In addition, an impurity wiper is arranged in the area of this opening via a holder.
During the course of the spinning process both coarse impurity components as well as fine impurity particles and fiber fluff are removed through the impurity-separation openings. The coarse impurity components as well as a portion of the fine impurity particles and the fiber fluff are discharged directly onto the impurity removal belt to be removed immediately as it moves along the air conduit. However, some of the remaining fine impurity particles and the fiber fluff settle at first in the area of the impurity-discharge openings of the sliver opening devices and are removed from there by the wiper.
The wiper is permanently arranged on the impurity-removal belt in the area of aforesaid the impurity-discharge openings and is moved with the conveyor belt along the air conduit. Thus, the wiper passes simultaneously with the opening into the area of a spinning location, where it mechanically separates the fine impurity components and the fluff from the guide walls of the sliver opening device. The separated impurity particles are then removed by suction through the opening into the air conduit.
As is the case in the other known impurity-removal devices, in German Patent Publication DE-AS 26 34 770 the wiper is also permanently arranged on the impurity conveyor belt. That is, the wiper is constantly moved back and forth between reversing points in the area of the end frames of the machine by the conveyor belt driven in a reciprocating manner. The reversal of the direction of motion of the conveyor belt takes place via switching elements which are arranged in the area of the end frames of the machine and are actuated by the holder of the wiping element.